Winter '17 / '18 - Snow Storm #3: Call for Forecasts

Windsor County ... NH

Fast moving storm in a progressive flow regime and marginal low-level temperature profiles are not the best set-up for a contest-worthy storm; however ... NWP sometimes doesn't catch on until the last minute so we/ll hope for the best.

Contest for Snow Storm #3 may be cancelled prior to the deadline if fewer than six stations are likely to observe at least a 4" snowfall.

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Forecast element:  each station's verification period snowfall
Deadline for entries:  10:30 PM EST ... TUE ... 16-JAN-18
Verification begins:  12:01 AM EST ... WED ... 17-JAN-18
Verification ends:  11:59 PM EST ... WED ... 17-JAN-18

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Enter your forecast at the NEWxSFC/s home page here.  http://www.newx-forecasts.com/
Follow the top-of-page link from 'Enter Storm Forecast.

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As always ... there/s no cost ... no fee ... no advertising ... or annoying requests for personal information to enter a forecast.  It's just a fun exercise for winter wx enthusiasts to see who can make the best synoptic-scale snowfall forecast.  See how well your forecast stacks up against NWS Eastern Region Weather Forecast Offices.

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If you are issuing your first forecast this winter...or you entered the 'season-total' forecast contest ... you/ll need to create an account (user name / password / valid e-mail ... if you want a copy of your forecast sent to your Inbox). sent to your Inbox.

Winter '17 / '18 - Snow Storm #2: FINAL Results

Forecasters' station verifications and the storm summary at NEWxSFC/s home page.
http://www.newx-forecasts.com/

	1st - Brad Yehl
	SUMSQ:	107
	SUMSQ Z:	-1.566
	STP:	19.9	(3)
	TAE:	42.8	(1)
	AAE:	1.58	(1)
	2nd - WeatherT
	SUMSQ:	156
	SUMSQ Z:	-1.220
	STP:	23.1	(4)
	TAE:	46.1	(2)
	AAE:	1.71	(2)
	3rd - Shillelagh
	SUMSQ:	190
	SUMSQ Z:	-0.977
	STP:	23.2	(5)
	TAE:	56.6	(3)
	AAE:	2.10	(3)
	HM - donsutherland1
	SUMSQ:	215
	SUMSQ Z:	-0.799
	STP:	42.9	(11)
	TAE:	56.7	(4)
	AAE:	2.10	(4)

SUMSQ:  sum of square errors (")
SUMSQ Z:  Z-score
STP:  storm total precipitation error (")
TAE:  total absolute error (")
AAE:  average absolute error (")
(#):  category rank


Forecast by Observed Snowfall Scatter Plots of Top Forecasters
Dotted blue line below (above) solid red line ==> under (over) forecast


Station Verification Comparison of Top Forecasters

Snowfall Distribution and Magnitude by Station (Power Map - Excel 2013)


Melt-water Distribution and Magnitude by Station (Power Map - Excel 2013)

Winter '17 / '18 - Snow Storm #2: Preliminary STP Verifications

Table of preliminary storm-total snowfall by station for THU and FRI from CDUS41 (CLI) ... CXUS51 (CF6) and ... SAUS41 (METAR) bulletins.

Exceptions:
SBY
04-JAN and 05-JAN CLI and CF6 bulletins carried 'MM' as daily snowfall at post-time.  Tipping bucket data unhelpful.

Estimated storm-total snowfall based on inverse distance weighting technique using the four closest STP reports carried in AKQPNS.  STP value subject to change pending updates to CDUS41 ... CXUS51 ... or PNS bulletins.

HYA
Estimated storm-total snowfall based on METARs @ 10:1 SLR.

Suspect SLRs at ORH ...PVD ... and BGM ... a likely consequence of the storm's high-wind conditions.  Looks like BDR applied 10:1 to derive melt-water given hinky 6- and 7-group data.

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Stations observing at least:
Trace - 27 (100% - something for everyone.  RDU 0.9" fell during pre-deadline hours)
4" - 18 (67%)
6" - 14 (52%)
8" - 14 (52%)
10" - 10 (37%)
12" - 9 (33%)
14" - 5 (19%)
16" - 4 (15%)
18" - 2 (17%)
20" - 0

Max melt-water at ISP (1.53")
CAR - 1.36"
BDR / ACY - 0.80"
BGR - 0.79"

New daily records:  13
BGR - 18.3" (8.5"; 2003)
ISP - 16" (3.8"; 1988)
PVD - 14.1" (5.7"; 1988)
BOS - 13.4" (7.9"; 1994)
ACY - 13.2" (2.5"; 1905)
CAR - 13" (10.5"; 1988)
BDL - 10.2" (8.1"; 1923)
SBY - 8.5" (0.9"; 1952)
EWR - 8.4" (4"; 1988)
BDR - 8" (5.3"; 1988)
JFK - 8" (4.9"; 1988)
ORF - 5.1" (1.2"; 1905)
RIC - 2.4" (1.6"; 1980)

Surface analysis:  18z ... 04-JAN-18

Central pressure:  950 mb
 

 Daily weather map for 04-JAN-88.
 

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Please report any errors in Comments along with a link to the correct data.
Final results expected NLT SUN evening.

Winter '17 / '18 - Snow Storm #2: The Forecasts

Rookie 0
Intern 1
Journey 1
Senior 12
GOVT 1
TOT 15

All forecasts posted to the Contest/s web site.
Direct link:  http://www.newx-forecasts.com/NEWxSFC_19/storms/storm2_forecasts_04Jan18.htm

Forecasts ranked by their storm-total precipitation (STP).


BLUE ==> 25th percentile
RED ==> 75th percentile
White STP and 4cast cells range between the 25th and 75th percentile
GOVT (NWS) forecasts derived from current issuances at the deadline.

Heaviest snowfall (>= 10") consensus along and to the right of CAR - BGR - PWM - BOS - PVD - ISP - ORH - CON - PWM - CAR.  Snow cones expected at BGR and CAR.  All forecast stations get a share of the wealth; however ... stations well inland left to experience the storm/s best effects via TV and social media.

High amplitude flow regime captured by PNA > 1.  Sad sack NAO off wandering alone in the wilderness ... unimpressed by AO sibling/s dramatic cliff dive.

Median station forecasts (Excel Power Map)

Winter '17 / '18 - Snow Storm #2: RAW FORECASTS

Here

Winter '17 / '18 - Snow Storm #2: Call for Forecasts

High-amplitude flow regime with shortening wavelength poised to excite cyclogenesis off the SE coast on WED then deepen rapidly along the VA / NC coast early THU as it heads toward the M-A and SNE coast.

Accumulating snows may be observed at southern forecast stations before the verification period begins; therefore ... forecasters should EXCLUDE these amounts from their forecasts.

Contest may be cancelled before deadline if storm appears not to be contest-worthy.

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Forecast element: station total snowfall

Deadline for entries:  WED ... 03-JAN-18 @10:30 PM EST
Verification begins:  THU ... 04-JAN-18 @ 12:01 AM EST
Verification ends:  FRI ... 05-JAN-18 @ 11:59 PM EST

Enter your forecast at the NEWxSFC/s home page @ http://www.newx-forecasts.com/
Follow the top-of-page link from 'Enter Storm Forecast'
Contest rules

----
As always ... there/s no cost ... no fee ... no advertising ... or annoying requests for personal information to enter a forecast.  It's just a fun exercise for winter wx enthusiasts to see who can make the best synoptic-scale snowfall forecast.

---
If you are issuing your first forecast this winter ... or you entered the 'season-total' forecast contest ... you/ll need to create an account (user name / password / valid e-mail ... if you want a copy of your forecast sent to your Inbox.

Winter '17 / '18 - Temperature Departure From Normal: Progress Report - December

Winter '17 / '18 - Coastal Teaser #1

Snow Storm #2 may be in the cards later this week as an Arctic air mass in a high amplitude flow regime excites cyclogenesis along the SE coast where SST are anomalously warm.

Latest progs suggest nuisance snow amounts may begin accumulating over extreme southern forecast stations around sundown on WED ... several hours before the deadline.

Don't see any reason to set the deadline for entries TUE evening to ensure these stations are in the mix when this system/s main event will likely play out farther north on THU.

Should the present trend in NWP output continue ...
Call for Forecasts:  TUE ... 02-JAN-18
Deadline for entries:  10:30 PM EST ... WED ... 03-JAN-18
Verification period begins:  12:01 AM EST ... THU ... 04-JAN-18
Verification period ends:  11:59 PM EST ... FRI ... 05-JAN-18

Winter '17 / '18 - Snow Storm #1: FINAL Results

Forecasters' station verifications and the storm summary at NEWxSFC/s home page.
http://www.newx-forecasts.com/

	1st - JessicaCain
	SUMSQ:	17
	SUMSQ Z:	-0.991
	STP:	4.3	(4)
	TAE:	12.0	(1)
	AAE:	0.63	(1)
	2nd - TQ
	SUMSQ:	24
	SUMSQ Z:	-0.858
	STP:	4.7	(5)
	TAE:	14.3	(2)
	AAE:	0.75	(2)
	3rd - Shillelagh
	SUMSQ:	25
	SUMSQ Z:	-0.847
	STP:	3.6	(3)
	TAE:	14.4	(3)
	AAE:	0.76	(3)
	HM - WeatherT
	SUMSQ:	33
	SUMSQ Z:	-0.685
	STP:	0.4	(2)
	TAE:	17.4	(5)
	AAE:	0.92	(5)

SUMSQ:  sum of square errors (")

STP:  storm total precipitation (")

TAE:  total absolute error (")
AAE:  average absolute error (")

(#): rank

Forecast by Observed Snowfall Scatter Plots of Top Forecasters 

 

Station Verification Comparison of Top Forecasters

 

Snowfall Distribution and Magnitude by Station (Power Map - Excel 2013)

 

 

Winter '17 / '18 - Snow Storm #1: Preliminary STP Verification

Table of preliminary storm-total snowfalls by station for MON from CDUS41 and CXUS51 bulletins.

Exceptions:
PWM and CON
25-DEC/s daily CLI and CF6 bulletins carry 'MM' as daily snowfall at post-time. 
Preliminary verification STP from latest PNSGYX and METARs.
Values subject to change pending updates to CDUS41 ... CXUS51 ... or PNS bulletins.

HYA
Storm-total snowfall report based on METARs

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Stations observing at least:
Trace - 19
4" - 6
6" - 1
8" - 1
10" - 0

Max melt-water at BGR (0.46")
Snow-Liquid Ratios (SLR) for areas with mixed precipitation ... such as BDR and BOS ... are not reported.

12z 12-25-17

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Please report any errors in Comments along with a link to the correct data.
Final results expected NLT WED evening.